The present invention relates to a closed type scroll compressor suitable for use in a refrigeration cycle of an air conditioner, refrigerator or the like system and, more particularly, to a closed type scroll compressor having an improved lubricating system for lubricating a bearing of the compressor.
Japanese Unexamined Patent Publication No. 2-157493 discloses a closed type scroll compressor having a lubricating system, with the scroll compressor including a motor cover disposed near an end of a drive shaft adjacent to a driving motor and a bearing for supporting the end of the drive shaft. The motor cover is fixed to a frame by bolts. A lubricating oil pipe is provided between the motor cover and a lubricating oil reservoir, thus providing a lubricating oil passage for lubricating the bearing.
Japanese Patent Application No. 1-271661 (Unexamined Patent Publication 3-134,288) discloses a scroll compressor having a different type of lubricating system, wherein a lubricating oil pump is provided on the end surface of a drive shaft adjacent a driving motor. The lubricating oil pump is supported by bolts which serve to fix the stator of the driving motor. The lubricating oil pump is mounted by using a resilient force of a spring such that a gap is formed between the lubricating oil pump and a housing, so as to be able to rotate relative to the housing. The lubricating oil is driven to lubricate a bearing of the compressor.
In the known scroll compressors of the type described above, the member providing the lubricating oil passage on the end of the drive shaft near the driving motor is fixed to the motor or to the frame by screws or bolts and, therefore, is substantially fixed with respect to the axis or center of the drive shaft. The known arrangement can suitably be employed in the case where the compressor is completed by assembling the compression mechanism portion, drive shaft, motor portion and the lubricating oil passage and then mounting these assembled parts as a unit in a hermetic casing. However, the known arrangement cannot be adopted in the case where, for example, the stator of the motor is press-fitted in the hermetic casing because, in such a case, no bolt is available for fixing the member defining the lubricating oil passage.
This problem is serious particularly in the compressor of the type proposed in Japanese Patent Application No. 1-271661. Namely, in this type of compressor, the cover is inclined as a result of an inclination of the end surface of the motor, which causes an unevenness in the bearing gap between the bearing surface and the shaft, leading to a serious problem such as burning of the bearing. Furthermore, assembly cannot be conducted easily due to difficulty encountered in locating the lubricating oil pipe to the cover when the pipe is to be connected to the cover.
The arrangement disclosed in Japanese Unexamined Patent Publication No. 2-157493 is adoptable only when the oil reservoir is formed as a part of the hermetic casing. Namely, this arrangement cannot apply to a case where the oil reservoir is formed separately from the hermetic casing. It is not practical to extend the lubricating oil pipe to the exterior of the hermetic casing, considering difficulty encountered in assembly of the compressor.